Problem solved. I obtained a service manual online. There are two fixes for this error code. 1) Replace the cartridge (did that to no avail). And 2) “Check the connection between the CSIC and the main board, and fix any abnormality.” A CSIC appears to be an ink cartridge sensor (_ _ integrated circuit?). Before disassembling the printer to inspect the main board, I tried jiggling the cartridge a few times. The printer recognized the cartridge and the error code resolved.